The invention relates to an apparatus on the carousel principle for coating substrates, having a vacuum chamber and a rotatable substrate holder disposed in the latter. The apparatus has a plurality of substrate pickups in a circular arrangement at equal distances apart, and by which a corresponding number of substrates are transportable step-wise by means of a drive, on a circular path from an air lock station through at least one coating station to the air lock station.
The manner of operation of such an apparatus can be considered to be quasi-continuous on account of the stoppage between the individual steps, necessitated by the entrances and exits through the locks as well as by the stationary coating process.
U.S. Pat. No. 3,652,444 has disclosed an apparatus of the kind described above, which has three coating stations but only one air lock station. The known apparatus is intended for the production of semiconductors, and usually the various coating stations serve in this case for the application of a whole series of coatings. The coating stations can be preceded and followed by other treatment stations in which other treatment processes are performed, as necessary for the pre-treatment and post-treatment of semiconductors. For a given pitch diameter and corresponding investment costs, however, the throughput is limited, if only because entering and leaving the air locks including the evacuation of the air lock chamber require a suitable length of time.
There are a number of coating tasks and products in which the coating process itself and/or the pre-treatments and/or post-treatments call for a lesser expenditure of time, so that the use of the known apparatus for such processes or products would be extremely uneconomical. An example of such products is the so-called CD record which is to be provided on only one side with a single coat of a quickly applied highly reflective metal such as aluminum, for example.
Also important in the operation of such apparatus are the so-called loading stations with which the all-automatic loading and unloading of such apparatus is possible. Such loading stations in conjunction with their corresponding magazine stations are relatively complex and their cycling frequency cannot be fully utilized on account of the relatively slow manner of operation of the known apparatus.
The invention is therefore based on the task of improving an apparatus of the kind described above such that the throughput can be substantially increased at approximately comparable investment costs.